1. Field of the Invention
The present invention relates to a chucking mechanism used in a slim disk driving apparatus, and to a disk driving apparatus including a brushless motor including the chucking mechanism.
2. Description of Related Art
Conventionally, a disk having two disks pasted to one another by adhesive and a hole at a center thereof (hereafter, simply referred to as “multi-layered disk”) has been used widely. Due to an increased demand for a slimmer disk driving apparatus, a method to retain the multi-layered disk has been changing from a clamping method in which the multi-layered disk is clamped to a method in which a chucking mechanism having a plurality of claw members supplying radial tension to the hole at the center of the multi-layered disk retains the multi-layered disk.
Hereinafter, a conventional chucking mechanism 1 will be described with reference to FIGS. 11 and 12. FIG. 11 is a schematic cross sectional view of the chucking mechanism 1 prior to retaining a multi-layered disk 2. FIG. 12 is a schematic cross sectional view of the chucking mechanism 1 in which a claw member 1b is at a radially innermost position.
According to FIG. 11, the chucking mechanism 1 preferably includes a center case 1a around which an inner edge of a central opening 2a of a multi-layered disk 2 (not shown in FIG. 11, see FIG. 12) will be arranged, a claw member 1b retaining the inner edge of the central opening 2a, an elastic member 1c providing radial force to the claw members 1b, and a turn table 1d having a mounting portion 1d1 on which the multi-layered disk 2 will be mounted. Also, the center case preferably includes at a portion thereof corresponding to the claw member 1b a protrusion 1a1 having a sliding surface 1a2 on which the claw members 1b slides.
It is to be appreciated that the adhesive may not be appropriately applied when forming the multi-layered disk 2, in particular at a portion near the central opening 2a, and therefore, a gap 2b may be formed when a force is applied to the central opening 2a. When the multi-layered disk 2 having such gap at the central opening 2a is placed on the chucking mechanism as described above, the multi-layered disk 2 will not be retained appropriately (see FIG. 12).